Purchase this article with an account.
Liu-Fang Zhou, Simona Buetti, Shena Lu, Yong-Chun Cai; How does attention alter perceived contrast? Enhancement at low contrast levels turns into attenuation at high contrast levels.. Journal of Vision 2017;17(10):48. doi: 10.1167/17.10.48.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
It has been a long-standing question of whether attention alters appearance. A recent landmark study demonstrated that attention enhances apparent contrast (Carrasco, Ling, & Read, 2004, Nature Neuroscience). One shortcoming of the tasks used in this type of study is that they are prone to induce cue-related response biases. Here we used two opposite tasks to isolate the response bias in these tasks. Participants were presented with an abrupt cue and two gratings afterward, and were instructed to report the orientation of the stimulus which looked higher (Experiment 1) or lower (Experiment 2) in contrast. By comparing performance across experiments, the reversal of instructions allows to better estimate the magnitude of observed response biases and therefore to better isolate the effects of attention on apparent contrast. We also systematically study attentional effects over a wide range of contrast levels (15-60%). When using a higher comparative task, we found a boost of apparent contrast by attention with low-contrast stimuli (15% and 25%), but null effects with high-contrast stimuli (40% and 60%). When using a lower comparative task, surprisingly, an attentional attenuation of apparent contrast was found at high contrast levels, whereas no effect was found at low contrast levels. Thebetween-experiment analysis demonstrated that the observed effect was an addictive combination of a perceptual effect induced by attention and response bias to report the item on the side where the cue was presented. After isolating the two effects, we were able todemonstrate that attention alters perceived contrast in a contrast-dependent way: attention enhances contrast at low contrast levels, but attenuates it at high contrast levels.
Meeting abstract presented at VSS 2017
This PDF is available to Subscribers Only